Re: Ceph cluster stability

[M Ranga Swami Reddy <swamireddy-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>]

We have taken care all HW recommendations, but missing that ceph mons
are VMs with good configuration (4 core, 64G RAM + 500G disk)...
Is this ceph-mon configuration might cause issues?

On Sat, Feb 23, 2019 at 6:31 AM Anthony D'Atri <aad@dreamsnake.net> wrote:
>
>
> ? Did we start recommending that production mons run on a VM?  I'd be very hesitant to do that, though probably some folks do.
>
> I can say for sure that in the past (Firefly) I experienced outages related to mons running on HDDs.  That was a cluster of 450 HDD OSDs with colo journals and hundreds of RBD clients.  Something obscure about running out of "global IDs" and not being able to create new ones fast enough.  We had to work around with a combo of lease settings on the mons and clients, though with Hammer and later I would not expect that exact situation to arise.  Still it left me paranoid about mon DBs and HDDs.
>
> -- aad
>
>
> >
> > But ceph recommendation is to use VM (not even the  HW node
> > recommended). will try to change the mon disk as SSD and HW node.
> >
> > On Fri, Feb 22, 2019 at 5:25 PM Darius Kasparavičius <daznis@gmail.com> wrote:
> >>
> >> If your using hdd for monitor servers. Check their load. It might be
> >> the issue there.
> >>
> >> On Fri, Feb 22, 2019 at 1:50 PM M Ranga Swami Reddy
> >> <swamireddy@gmail.com> wrote:
> >>>
> >>> ceph-mon disk with 500G with HDD (not journals/SSDs).  Yes, mon use
> >>> folder on FS on a disk
> >>>
> >>> On Fri, Feb 22, 2019 at 5:13 PM David Turner <drakonstein@gmail.com> wrote:
> >>>>
> >>>> Mon disks don't have journals, they're just a folder on a filesystem on a disk.
> >>>>
> >>>> On Fri, Feb 22, 2019, 6:40 AM M Ranga Swami Reddy <swamireddy@gmail.com> wrote:
> >>>>>
> >>>>> ceph mons looks fine during the recovery.  Using  HDD with SSD
> >>>>> journals. with recommeded CPU and RAM numbers.
> >>>>>
> >>>>> On Fri, Feb 22, 2019 at 4:40 PM David Turner <drakonstein@gmail.com> wrote:
> >>>>>>
> >>>>>> What about the system stats on your mons during recovery? If they are having a hard time keeping up with requests during a recovery, I could see that impacting client io. What disks are they running on? CPU? Etc.
> >>>>>>
> >>>>>> On Fri, Feb 22, 2019, 6:01 AM M Ranga Swami Reddy <swamireddy@gmail.com> wrote:
> >>>>>>>
> >>>>>>> Debug setting defaults are using..like 1/5 and 0/5 for almost..
> >>>>>>> Shall I try with 0 for all debug settings?
> >>>>>>>
> >>>>>>> On Wed, Feb 20, 2019 at 9:17 PM Darius Kasparavičius <daznis@gmail.com> wrote:
> >>>>>>>>
> >>>>>>>> Hello,
> >>>>>>>>
> >>>>>>>>
> >>>>>>>> Check your CPU usage when you are doing those kind of operations. We
> >>>>>>>> had a similar issue where our CPU monitoring was reporting fine < 40%
> >>>>>>>> usage, but our load on the nodes was high mid 60-80. If it's possible
> >>>>>>>> try disabling ht and see the actual cpu usage.
> >>>>>>>> If you are hitting CPU limits you can try disabling crc on messages.
> >>>>>>>> ms_nocrc
> >>>>>>>> ms_crc_data
> >>>>>>>> ms_crc_header
> >>>>>>>>
> >>>>>>>> And setting all your debug messages to 0.
> >>>>>>>> If you haven't done you can also lower your recovery settings a little.
> >>>>>>>> osd recovery max active
> >>>>>>>> osd max backfills
> >>>>>>>>
> >>>>>>>> You can also lower your file store threads.
> >>>>>>>> filestore op threads
> >>>>>>>>
> >>>>>>>>
> >>>>>>>> If you can also switch to bluestore from filestore. This will also
> >>>>>>>> lower your CPU usage. I'm not sure that this is bluestore that does
> >>>>>>>> it, but I'm seeing lower cpu usage when moving to bluestore + rocksdb
> >>>>>>>> compared to filestore + leveldb .
> >>>>>>>>
> >>>>>>>>
> >>>>>>>> On Wed, Feb 20, 2019 at 4:27 PM M Ranga Swami Reddy
> >>>>>>>> <swamireddy@gmail.com> wrote:
> >>>>>>>>>
> >>>>>>>>> Thats expected from Ceph by design. But in our case, we are using all
> >>>>>>>>> recommendation like rack failure domain, replication n/w,etc, still
> >>>>>>>>> face client IO performance issues during one OSD down..
> >>>>>>>>>
> >>>>>>>>> On Tue, Feb 19, 2019 at 10:56 PM David Turner <drakonstein@gmail.com> wrote:
> >>>>>>>>>>
> >>>>>>>>>> With a RACK failure domain, you should be able to have an entire rack powered down without noticing any major impact on the clients.  I regularly take down OSDs and nodes for maintenance and upgrades without seeing any problems with client IO.
> >>>>>>>>>>
> >>>>>>>>>> On Tue, Feb 12, 2019 at 5:01 AM M Ranga Swami Reddy <swamireddy@gmail.com> wrote:
> >>>>>>>>>>>
> >>>>>>>>>>> Hello - I have a couple of questions on ceph cluster stability, even
> >>>>>>>>>>> we follow all recommendations as below:
> >>>>>>>>>>> - Having separate replication n/w and data n/w
> >>>>>>>>>>> - RACK is the failure domain
> >>>>>>>>>>> - Using SSDs for journals (1:4ratio)
> >>>>>>>>>>>
> >>>>>>>>>>> Q1 - If one OSD down, cluster IO down drastically and customer Apps impacted.
> >>>>>>>>>>> Q2 - what is stability ratio, like with above, is ceph cluster
> >>>>>>>>>>> workable condition, if one osd down or one node down,etc.
> >>>>>>>>>>>
> >>>>>>>>>>> Thanks
> >>>>>>>>>>> Swami
> >>>>>>>>>>> _______________________________________________
> >>>>>>>>>>> ceph-users mailing list
> >>>>>>>>>>> ceph-users@lists.ceph.com
> >>>>>>>>>>> http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
> >>>>>>>>> _______________________________________________
> >>>>>>>>> ceph-users mailing list
> >>>>>>>>> ceph-users@lists.ceph.com
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>
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